Safety arrangement

ABSTRACT

A lifting unit ( 1 ) to lift the rear part of a hood or bonnet in the event that an accident should arise comprises an inner cylindrical guide ( 2 ) to receive gas from a gas generator and telescopically mounted on the guide, to telescopically interconnected cylindrical piston elements ( 12, 17 ). There is a certain degree of play between the telescopically interconnected units to facilitate a virtual pivoting movement of the hood or bonnet to be lifted by the lifting unit.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to PCT/SE2003/001823, filed Nov. 26,2003 and GB 0227809.1, filed Nov. 28, 2002.

FIELD OF THE INVENTION

The present invention relates to a safety arrangement and moreparticularly to a safety arrangement provided in a motor vehicle adaptedto lift the rear part of the hood or bonnet of the vehicle in responseto an impact or accident situation involving a pedestrian.

BACKGROUND OF THE INVENTION

It has been proposed to provide a safety arrangement adapted to raisethe rear part of the hood or bonnet of the motor vehicle in the eventthat an accident should occur in which a pedestrian is involved. Thereason for lifting the rear part of the hood or bonnet is that, with therear part of the hood or bonnet lifted, the entire bonnet is spaced fromthe underlying engine. The hood or bonnet may thus deform, whilstdecelerating the body or head of the pedestrian, thus giving the head orbody of the pedestrian a relatively slow deceleration. If the hood orbonnet were not lifted and the hood or bonnet deformed downwardly byeven a short distance due to an impact with a pedestrian, that downwardmovement would soon terminate when the underside of the hood or bonnetimpacted with the underlying engine, thus very rapidly decelerating thepedestrian with possible injury consequences.

Various proposals have been put forward as to mechanisms to achieve thisobjective, but it has been found difficult to provide a mechanismdimensioned to be located beneath the hood or bonnet, but which iscapable of providing a sufficient degree of lift. The present inventionseeks to provide an improved safety arrangement.

SUMMARY OF THE INVENTION

According to one aspect of this invention there is provided a liftingunit for lifting the rear part of a hood or bonnet. The lifting unitcomprises a hollow cylindrical guide and at least one piston moveablerelative to the hollow cylindrical guide and the piston being of hollowcylindrical form.

Preferably the unit incorporates two pistons each moveable relative tothe guide and each moveable relative to the other piston.

Advantageously both of the pistons are of hollow cylindrical form. Thetwo pistons are telescopically inter-engaged and the innermost pistontelescopically engaging the cylindrical guide.

Alternatively the unit incorporates one cylindrical piston moveablerelative to the guide and one piston comprising a piston head and apiston rod moveable relative to the cylindrical piston.

Preferably the piston rod is connected to the piston head by a yieldablecoupling to enable the piston rod to be deflected from an initial axisof movement of the piston.

Alternatively the piston head is provided with a peripheral resilientsealing ring to facilitate deflection of the piston rod from an initialaxis of movement of the piston rod.

In a further embodiment of the invention, the lifting unit defines aninner guide cylinder and an outer cylindrical guide sleeve. Acylindrical piston is located between the inner guide cylinder and theouter guide sleeve.

Preferably an outer part of the inner guide sleeve defines a groove andan inner part of the cylindrical piston defines a groove. The groovesare co-aligned when the piston is an initial condition relative to theguide cylinder and a releasable element is contained within theco-aligned grooves to retain the piston in the initial condition.

Conveniently the outer guide sleeve is provided with a re-entrant topportion configured to engage a piston head provided on the cylindricalpiston.

According to another aspect of this invention there is provided alifting unit for lifting part of a hood or bonnet. The lifting unitcomprises a plurality of with at least one element being moveablerelative to another element along a predetermined axis. The lifting unitis mounted or configured so that when the lifting unit is actuated, atleast part of the lifting unit may deviate from the axis to facilitatethe effecting of a virtual pivoting movement of the rear part of a hoodor bonnet.

Preferably the entire lifting unit is mounted to be tilted from aninitial position.

Conveniently the lifting unit is mounted with an abutment face presenton the lifting unit engaging a resilient element mounted on a support.The resilient element is configured to be deformed to permit thetilting.

Advantageously the lifting unit comprises a plurality of elements. Atleast one element is moveable relative to another element along apredetermined axis, at least one part of the unit being yieldable toenable one element to be deflected from said axis on deployment of thelifting element.

Preferably the lifting element incorporates a piston having a pistonhead and a piston rod. The piston rod is connected to the piston headwith a yieldable coupling so that the piston rod may become deflectedfrom the axis of movement of the piston.

Conveniently the piston rod has a relatively narrow portion which passesthrough an aperture formed in part of the piston head. A resilientwasher is trapped adjacent the piston head by a flange provided on thepiston rod.

In an alternative embodiment, a piston is provided with a resilientsealing washer capable of deforming to permit one element of the liftingunit to become inclined.

Advantageously a piston is provided with a mounting lug provided with anaperture to receive a pivot pin.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood, and so thatfurther features thereof may be appreciated, the invention will now bedescribed, by way of example, with reference to the accompanyingdrawings in which:

FIG. 1 is a perspective view of a lifting unit in accordance with thepresent invention;

FIG. 2 is a side view of the lifting unit of FIG. 1;

FIG. 3 is a plan view of a gas generator housing for use with the unitof FIG. 2;

FIG. 4 is a sectional view of the unit of FIG. 2 and the associated gasgenerator housing in an initial position;

FIG. 5 is a view generally corresponding to FIG. 4, but taken from theopposite side, showing the unit of FIGS. 1 to 4 after deployment;

FIG. 6 is an exploded view of some of the components of an alternativeembodiment of the invention;

FIG. 7 is a sectional view of the alternative embodiment of theinvention prior to deployment;

FIG. 8 is a view corresponding to FIG. 7 illustrating the unit of FIG. 6following deployment;

FIG. 9 is a sectional view of a further embodiment of the inventionprior to deployment;

FIG. 10 is a sectional view of the embodiment of FIG. 8 followingdeployment;

FIG. 11 is a view of yet another embodiment of the invention prior todeployment;

FIG. 12 is a view corresponding to FIG. 10 showing the embodiment ofFIG. 10 following deployment;

FIG. 13 is a sectional view of another embodiment prior to deployment;

FIG. 14 is a view of the embodiment of FIG. 12 following deployment;

FIG. 15 is an enlarged perspective view of components of the embodimentof FIGS. 13 and 14; and

FIG. 16 is a side elevational and part sectional view of anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIGS. 1 to 5 of the accompanying drawings, alifting unit 1 is illustrated. The lifting unit includes an inner hollowcylindrical guide 2. The guide 2 is provided, at its lower end, with aprojecting neck 3. The neck 3 is adapted to be inserted into a recess 4contained within a housing 5. The housing 5 defines a second recess 6adapted to receive a gas generator. The neck 3 is provided with a gasinlet aperture 7 so that the gas from the gas generator may flow intothe interior of the cylindrical guide 2 that is associated with the neck3.

The upper end of the cylindrical guide 2 is partially sealed by an uppercap 8. The upper cap 8 is provided with a central gas flow passage 9therethrough. The outer periphery of the upper cap 8 is provided with agroove 10 containing a sealing ring 11. The sealing ring 11 engages theinterior of a first inner hollow moveable cylinder 12, the moveablecylinder 12 telescopically receiving almost the whole of the innercylinder 2.

The first moveable cylinder 12 has its own upper cap 13 which defines acentral gas flow passage 14 and which itself has an outercircumferential groove 15 which contains a sealing ring 16. The sealingring 16 sealingly engages the interior of a second hollow outer moveablecylinder 17. The upper cap 13 of the first moveable cylinder 12 has adepending circumferential skirt which closely embraces the upper part ofthe first moveable cylinder 12. The second moveable cylinder 17telescopically receives the combination of the inner cylinder 2 and thefirst moveable cylinder 12. The second moveable cylinder 17 is providedwith an end sealing cap 18, the end sealing cap 18 having a centralprojection 19.

The entire unit 1 is relatively compact and may readily be mounted inposition beneath the rear part of the hood or bonnet of a motor vehicle.

It is to be understood that, should an accident arise involving animpact of the vehicle with a pedestrian, gas will be generated and willflow through the apertures 7 into the neck 3 and thus into the hollowinterior of the cylindrical guide 2. It will be possible to achieve asubstantial flow rate of gas since the gas will not initially be fedinto an extremely small chamber, but instead will be fed into the entirehollow interior of the cylindrical guide 2. Gas will flow through theoutlet port 9 provided in the sealing closure 8, and will cause thefirst moveable cylinder 12 and the outer moveable cylinder 17 to moveaxially. The cylinders are guided, one on the other and the firstmoveable cylinder 12 is guided on the inner cylindrical guide 2. Theentire combination of cylinders will expand telescopically to have asubstantial length as shown in FIG. 5.

It can be seen that because there are two moveable hollow cylinders 12and 17, each of which has a length substantially equal to that of theinner cylindrical guide 2, a total “lift” can be achieved which is equalto approximately twice the initial height of the unit 1.

Once the cylinders have “lifted” to the configuration shown in FIG. 5,there is a certain “play” between the interconnection of the adjacentcylinders enabling the uppermost tube 17 to tilt about the axis definedby the innermost guide cylinder 2. This may be of substantial benefitsince the rear part of a hood or bonnet, when lifted by the liftingunit, will effect a virtual pivotal movement about the retaining catchprovided at the front of the hood or bonnet.

Referring now to FIGS. 6 to 8 in an alternative embodiment of theinvention, a lifting unit 20 is provided with a housing 21 defining achamber or cavity 22 to receive a gas generator. The housing 21 isprovided with a peripheral mounting flange 23 and is also provided withan axially extending inner hollow guide cylinder 24. The inner guidecylinder 24 terminates with a closed end provided with a gas outletaperture 24 a. The portion of the inner guide cylinder 24 adjacent thechamber 22 containing the gas generator is thickened at 25, and thethickened portion 25 is provided with an outer peripheral semicirculargroove 26.

A hollow cylindrical piston 27 is provided which surrounds the innerguide cylinder 24. One end of the piston 27, adjacent to the thickenedportion 25 of the inner guide cylinder 24, is provided with a pistonhead 28. The piston head 28 is of annular form and in an initialposition surrounds the thickened portion 25 of the inner guide cylinder24, and is provided with an internal semicircular groove 29 which is inalignment with the semicircular groove 26 provided in the thickenedportion 25. A “C” clip 30 is retained within the co-aligned grooves,thus holding the cylindrical piston 27 in a predetermined initialcondition relative to the inner guide cylinder 24.

The upper end of the cylindrical piston 27 is sealed by means of asealing plug 31. The sealing plug 31 may be configured to be biasedagainst the underside of a hood or bonnet or may be configured to definea pivot axis on which part of the hood or bonnet may be pivotallymounted.

The housing 21 carries an outer hollow cylindrical guide sleeve 32. Theouter guide sleeve 32 extends upwardly from above the mounting flange 23so as to telescopically receive the cylindrical piston 27 and the innerguide cylinder 24. The outer guide sleeve 32 is formed of a deformablematerial and has, at its upper end, an inwardly folded re-entrantportion 33 which contacts the outermost part of the upper region of thecylindrical piston 27. The piston head 28 of the cylindrical piston 27is a sliding sealing fit within the outer guide sleeve 32.

Upon actuation of the gas generator the hollow cylindrical piston 27moves upwardly. The gas flows through the hollow interior of the innerguide cylinder 24 and through the gas outlet aperture 24 a into theinterior of the cylindrical piston 27. As the piston 27 moves upwardly,the piston 27 becomes disengaged from the guide cylinder 24. The pistonhead 28 is a sliding sealing fit within the guide sleeve 32, thecontinued generation of gas continues to force the piston 27 upwardly.The piston head 28 then engages the lower end of the re-entrant portion33 of the guide sleeve 32. This re-entrant portion 33 is then deformed,thus absorbing energy and terminating the upward movement of thecylindrical piston 27. The unit 20 then has the condition shown in FIG.8.

FIGS. 9 and 10 illustrate another embodiment of the invention in which alifting unit 40 comprises an outer cylindrical guide 41 of uniformcross-section with, at its upper end, an inwardly directed lip. Theguide 41 is provided, at its base, with a housing 42. The housing 42defines a chamber or cavity 43 to receive a gas generator. The gasgenerator is configured to direct gas into the interior of the guide 41.Contained within the guide 41 is a hollow cylindrical piston 44. Thepiston 44 is generally of uniform section, and is provided at its upperend with an inwardly directed lip. The piston 44 is provided with apiston head 45 adjacent to the housing 42. Piston head 45 defines anouter peripheral groove 46 which receives a sealing ring 47. The sealingring 47 effects a substantially sealing sliding fit within the outercylindrical guide 41.

Contained within the inner cylindrical piston 44 is a piston unit 48.The piston unit 48 has a piston rod 49 carrying, at its lower end, apiston head 50. The piston head 50 is provided with a peripheral andinner groove 51 containing a sealing ring 52 which engages the interiorof the cylindrical piston 44. The piston rod has a relatively narrowportion 53 above the lower terminal end of the piston rod. The narrowportion 53 extends through a corresponding aperture formed in a webconstituting a central part of the piston head 50, and also through aresilient washer 54 above the web. The piston rod 49 has enlarged flange55 which abuts the upper surface of the washer 54. Thus, the washer 54and the web of the piston head are trapped between the flange 55 and theend of the piston rod 49.

The uppermost end of the piston rod is engaged with an end cap 56 whichinitially covers the uppermost ends of the cylindrical guide 41 andcylindrical piston 44.

When gas is generated by a gas generator within the cavity 43 the pistonhead 50 of the piston unit 48 moves upwardly until it engages the lip atthe uppermost end of the cylindrical piston 44. The cylindrical piston44 also moves upwardly until the piston head 45 on the cylindricalpiston 44 engages the lip at the uppermost end of the outer guide 41.The lifting unit is then fully extended, as shown in FIG. 10.

It is to be appreciated that the piston rod 49 may be deflected slightlyfrom its initial axis due to the presence of the resilient washer 54between the flange 55 on the piston rod 49, and at the adjacent webforming part of the piston head 50. This may facilitate the opening ofthe rear part of the hood or bonnet since, when the rear part of thehood or bonnet is lifted, the rear part exhibits a virtual pivotalmotion about the fastening catch provided at the front of the hood orbonnet.

FIGS. 11 and 12 illustrate an embodiment of the lifting unit 58 inaccordance with this invention which is very similar to that describedwith reference to FIGS. 9 and 10, but in this embodiment the piston rod49 is securely connected to the piston head 50. Other features of theembodiment of FIGS. 11 and 12 are the same as described above withreference to FIGS. 9 and 10. The operation of the unit is the same asthat described with reference to FIGS. 9 and 10, but it is to beappreciated that when the conventional piston 48 is in the full extendedposition, the piston rod 49 may tilt about an axis defined in the regionof the piston head due to a slight flexibility provided by the sealingring 52. This again facilitates a virtual pivotal movement of theuppermost part of the piston.

FIGS. 13 and 15 illustrate a further embodiment of the invention. FIG.13 illustrates a lifting unit 60 in its initial condition. The liftingunit 60 incorporates a housing 61 defining a chamber 62 to receive a gasgenerator.

The upper part of the housing 61 supports an inner hollow guide cylinder63. The upper end of the guide cylinder 63 defines a gas outlet port 64.The base of the guide cylinder 63 is provided with a thickened region 65adjacent the housing 61. An annular peripheral groove 66 is provided andformed in the thickened region 65. The groove 66 contains a “C” clip 67.

A hollow cylindrical piston 68 is provided which is engagedtelescopically with the guide cylinder 63. The lowermost end of thecylindrical piston 68 is provided with a piston head 69. The piston head69 is provided with an inner annular groove 70 in a form correspondingto that of the annular groove 66 formed in the thickened base region 65of the hollow inner cylindrical guide 63. Contained within the groove isa resilient annular ring 71.

The annular piston head 69 is also provided with a peripheral groove 72provided in its radially outermost face. The peripheral groove 72containing a sealing ring 73.

The upper end of the cylindrical piston 68 is provided with a plug 74.The plug 74 is provided, at its outer end, with an upstanding lug 75.The lug 75 defines a through-bore 76 dimensioned to receive a pivot pin.Part of the hood or bonnet may be pivotally mounted on the pivot pin.

The housing 61 carries a hollow cylindrical outer guide sleeve 77. Thelowermost end of the guide sleeve 77 is crimped to the housing 61. Thepiston head 69 of the cylindrical piston 68 is a sliding sealing fitwithin the guide sleeve 77. The upper end of the guide sleeve 77 iscrimped to a annular mounting ring 78. The mounting ring 78 may be usedto mount the lifting unit 60 to an aperture formed in a support plate 79forming part of the vehicle. A wiper seal 80 may be provided at theupper end of the guide sleeve 77 adjacent the mounting ring 78. Thewiper seal 80 engages the outer surface of the cylindrical piston 68.

It is to be appreciated that the cylindrical piston 68 in an initialposition as shown in FIG. 13, with the combination of the “C” clip 67and the annular ring 71 in the co-aligned annular grooves 66 in athickened portion 65 at the base of the inner cylindrical guide 63 and70 formed in the inner face of the piston head 69, serve to retain thecylindrical piston 68 firmly in an initial position. Thus the aperturedlug 75 can provide a firm pivot point for the rear part of the hood orbonnet.

Upon actuation of the lifting unit, gas is supplied from the gasgenerator through the hollow cylindrical guide 63 to the interior of thecylindrical piston. The cylindrical piston 68 thus moves axially,lifting the lug 75.

When the cylindrical piston 68 has been lifted, it is possible for theaxis of the cylindrical piston 68 to deviate from the axis of thecylindrical guide 63 and the cylindrical sleeve 77. This enables a hoodor bonnet to effect a virtual pivoting motion about a front fasteningcatch.

FIG. 16 illustrates a further embodiment of the invention in which alifting unit 81, which may be a lifting unit having the same internaldesign as that of the lifting unit 60, is mounted in position so thatthe entire lifting unit may tilt or pivot from an initial verticalposition. Lifting unit 81 is provided with an outer cylindrical guide82, and carries at its lower end, an outwardly directed mounting flange83. Beneath the mounting flange 83, a housing 84 is provided to containa gas generator.

The upper end of the lifting unit is provided with an apertured lug 85.

The flange 83 rests on top of an annular resilient ring 86 resting on asupport 87, and is held in position by means of an annular retainer ring88 which has an inwardly directed lip which extends inwardly over theflange 83. It is to be appreciated that the lifting unit 81 may effect atilting or pivoting movement about an initial upright position so thatthe unit deviates from its initial position with part of the resilientring 86 beneath the flange 83 being consequently compressed. This againfacilitates a virtual pivoting movement of the hood or bonnet beinglifted by the lifting unit.

The features disclosed in the foregoing description, or the followingclaims, or the accompanying drawings, expressed in their specific formsor in terms of a means for performing the disclosed function, or amethod or process for attaining the disclosed result, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

1. A lifting unit for lifting the rear part of a hood or bonnet, thelifting unit comprising a hollow cylindrical guide and at least onepiston moveable relative to the hollow cylindrical guide, the pistonbeing of hollow cylindrical form.
 2. A lifting unit according to claim 1wherein the lifting unit further comprises two pistons each of thepistions moveable relative to the guide and each of the Pistons moveablerelative to the others of the pistons.
 3. A lifting unit according toclaim 2 wherein both of the pistons are of hollow cylindrical form, bothof the pistons being telescopically inter-engaged, the innermost of thepiston telescopically engaging the cylindrical guide.
 4. A lifting unitaccording to claim 2 wherein the lifting unit further comprises one ofthe pistons moveable relative to the guide and the one piston having apiston head and a piston rod moveable relative to the said cylindricalpiston.
 5. A lifting unit according to claim 4 wherein the piston rod isconnected to the piston head by a yieldable coupling to enable thepiston rod to be deflected from an initial axis of movement of thepiston rod.
 6. A lifting unit according to claim 4 wherein the pistonhead is provided with a peripheral resilient sealing ring to facilitatedeflection of the piston rod from an initial axis of movement of thepiston rod.
 7. A lifting unit according to claim 2 wherein the liftingunit defines an inner hollow cylindrical guide and an outer hollowcylindrical guide, the piston being located between the inner cylinderguide and the outer guide sleeve.
 8. A lifting unit according to claim 7wherein an outer part of the inner cylindrical guide defines a firstgroove and an inner part of the piston defines a second groove, thegrooves being co-aligned when the piston is an initial conditionrelative to the inner cylindrical guide, there being a releasableelement contained within the grooves to retain the piston in the initialcondition.
 9. A lifting unit according to claim 7 wherein the outerhollow guide sleeve is provided with a re-entrant top portion configuredto engage a piston head provided on the piston.
 10. A lifting unit forlifting a part of a hood or bonnet, the lifting unit comprising aplurality of elements, at least one of the elements being moveablerelative to another of the elements along a predetermined axis, thelifting unit being configured so that when the lifting unit is actuatedat least part of the lifting unit may deviate from the axis tofacilitate the effecting of a virtual pivoting movement of the rear partof the hood or bonnet.
 11. A lifting unit according to claim 10 whereinthe entire lifting unit is mounted to be tilted from an initialposition.
 12. A lifting unit according to claim 11 wherein the liftingunit is mounted with an abutment face present on the lifting unitengaging a resilient element mounted on a support, the resilient elementbeing configured to be deformed to permit the tilting.
 13. A liftingunit according to any one of claims 10 wherein at least one part of theunit being yieldable to enable one element to be deflected from the axison deployment of the lifting element.
 14. A lifting element according toclaim 10 wherein the lifting element incorporates a piston having apiston head and a piston rod, the piston rod being connected to thepiston head with a yieldable coupling so that the piston rod may becomedeflected from the axis.
 15. A lifting unit according claim 14 whereinthe piston rod has a relatively narrow portion which passes through anaperture formed in part of the piston head, a resilient washer beingtrapped adjacent piston head by a flange provided on the piston rod. 16.A lifting unit according claim 14 wherein the piston head is providedwith a resilient sealing washer capable of deforming to permit oneelement of the lifting unit to become inclined.
 17. A lifting unitaccording to claim 10 wherein a piston is provided with a mounting lugprovided with an aperture to receive a pivot pin.